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07-09-2012, 06:19 PM   #1
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Is the SDM failure rate really that bad

I am looking at getting the 60-250 on the weekend but was reading today about sdm problems should this keep me from buying Pentax lenses?

07-09-2012, 06:28 PM   #2
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Officially, its failure rate is no more than usual, whatever that means.
07-09-2012, 06:32 PM   #3
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Here you go SDM Reliability Survey - PentaxForums.com

I would not buy certain lenses secondhand but some others have almost no problems at all.
The DA*60-250 is safe to buy.
07-09-2012, 06:34 PM   #4
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SDM Reliability Survey Results - PentaxForums.com

This should answer any of your questions.

And don't forget to take into account that most people will not complain if their lens is good, but those who have issues will go looking for somewhere to tell their story so these results would be leaning even more toward an exaggerated failure rate.

From all accounts the 60-250 is an incredible lens so I wouldn't be scared away by this at all. If you still have a concern about it then get an extended warranty and you will be fine.

Edit: Same survey as Anvh posted, he was just a little quicker.


Last edited by Chaos_Realm; 07-09-2012 at 06:35 PM. Reason: Edit: Same survey as Anvh posted
07-09-2012, 06:37 PM   #5
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QuoteOriginally posted by wlachan Quote
Officially, its failure rate is no more than usual, whatever that means.
That's almost as obscure as "It's failure rate is no more than expected."

There are lots of posts about people overjoyed with their equipment here and on other forums. This dismissal of problems by blaming the person for complaining (however obliquely) just doesn't wash. I don't see posts about failures in the 55-300, or the limited primes (which cost less than the SDM zooms), or many other Pentax products. I do see complaints about the SDM Zooms and the K-r. It seems clear that they have issues beyond normal production and quality issues. Some have posted about having the same SDM lens fixed several times, are they just whiners?

Those charts make my point for me. The 18-135 DC has how many failures? Out of 100 or so, precisely 0. The 17-70 SDM has how many failures reported? Out of 80 or so, there are around 34 or so - a 42.5% failure rate. Are there SDM lenses that fail less often, yes and to be fair among the zooms the 60-250 (which is the most expensive) fails the least. But the point is that they fail, and at an astonishing rate - particularly given the princely sums demanded for them.

Last edited by Docrwm; 07-09-2012 at 06:52 PM.
07-09-2012, 06:44 PM   #6
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SDM = Silent Defective Motor.
07-09-2012, 07:32 PM   #7
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QuoteOriginally posted by Docrwm Quote
That's almost as obscure as "It's failure rate is no more than expected."

There are lots of posts about people overjoyed with their equipment here and on other forums. This dismissal of problems by blaming the person for complaining (however obliquely) just doesn't wash. I don't see posts about failures in the 55-300, or the limited primes (which cost less than the SDM zooms), or many other Pentax products. I do see complaints about the SDM Zooms and the K-r. It seems clear that they have issues beyond normal production and quality issues. Some have posted about having the same SDM lens fixed several times, are they just whiners?

Those charts make my point for me. The 18-135 DC has how many failures? Out of 100 or so, precisely 0. The 17-70 SDM has how many failures reported? Out of 80 or so, there are around 34 or so - a 42.5% failure rate. Are there SDM lenses that fail less often, yes and to be fair among the zooms the 60-250 (which is the most expensive) fails the least. But the point is that they fail, and at an astonishing rate - particularly given the princely sums demanded for them.
Sorry but a single lens can not proof or disproof anything. If pentax only had DA* primes then your conclusion would have been different.
Since we are discussing the motor for fun look at other brands, some of them also use the same type of motor and what are their failure rates?
The DC is also used, the budget Nikon and Canon lenses use them so if you want to have a complete picture then go ahead.

But keep it fair will you...
This discussion has been made hundreds of time already...

You can look on lesnrantals.com for some failure rates, i believe the average is 6% of all the lenses fail.

Last edited by Anvh; 07-09-2012 at 07:50 PM.
07-09-2012, 07:41 PM   #8
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just wondering can you turn off sdm on the 60-250 I see it also has screw drive.

07-09-2012, 07:43 PM   #9
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QuoteOriginally posted by coreyhkh Quote
just wondering can you turn off sdm on the 60-250 I see it also has screw drive.
Sadly you can't do that, I created a petition for that 2 1/2 years ago and Pentax never listened. Pentax SDM Firmware Petition
07-09-2012, 07:44 PM   #10
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QuoteOriginally posted by coreyhkh Quote
just wondering can you turn off sdm on the 60-250 I see it also has screw drive.
Short answer: no
07-10-2012, 04:00 AM   #11
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I think you need to understand that by having a motor in your lens, you definitely increase the chance that the lens will fail. They certainly will not last as long as the FA limiteds. At the same time, no one except Pentax truly has any numbers on these things. Anything you read or hear on this forum (including from me) is pure speculation.

It feels to me like the rate of SDM failure has gone down considerably over time (it's just a feeling). I currently own the DA *16-50, 50-135 and 55. The 50-135 I have owned the longest (4 years) and it has had no trouble. The 16-50 I have owned for 3 and 1/2 years and it required SDM replacemnt 5 months after purchase. Since then it has been fine. The 55 I have owned for 2 years and it has had no problems. Of course, this is only anecdotal evidence that things are better and there will be others who share stories about lenses that have required motor replacement multiple times.

In Canada, you will get a two year warranty with your lens as well and I wouldn't worry over much about it, although if it does worry you, you could consider a Mack Warranty to go with the lens. I know Prodigital 2000 offers these.
07-10-2012, 06:14 AM   #12
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To rub salt, the DC is so much more quicker, 100% reliable and cheaper than SDM. If one looks at the built of 16-50 and 18-135, the former (IMO) looks so much more complicated. After the road map excitement cooled down, everyone goes back to flogging the dead SDM horses, and Pentax, remain mum. I really hope to see a revised 16-50 f2.8 with better flare resistant and sharper wide open with WR DC. This is long overdue and prohibiting a lot of guys from jumping into the Pentax system. WR DC prime wouldn't hurt too.
07-10-2012, 08:48 AM   #13
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QuoteOriginally posted by lightbulb Quote
To rub salt, the DC is so much more quicker, 100% reliable and cheaper than SDM.
So you're saying that the next lens with DC will also be quicker and 100% reliable?

I'm so surprised how many good and reliable data some can draw by a single lens, it's a miracle.
For fun read a bit more into the 18-135 and you will read it has special rear elements tofocus faster with (sigma use this as well), so it's the lens design doing most of the work on the 18-135, no idea how much influence the DC has in that and even if they can move the bigger and better sealed elements in the DA* lenses.

About the build the DA*16-50 is far more complicated it has SDM, screwdrive, and quickshift, the DA18-135 doesnt have the screw drive.

Last edited by Anvh; 07-10-2012 at 09:08 AM.
07-10-2012, 08:51 AM   #14
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I have had my 17-70mm lens about 2 years, it's very sharp when it works. It's going in for the 2nd time, it fail to focus in the middle of a shoot so it's gone when it gets back. I had a Sigma back-up and finished the shoot with no more problems. I love the 17-70 Pentax but .......... Maybe Pentax should sell them in pairs. Whats with Pentax all the new products are either K-5 based or cheap. Pentax please quality first.

Last edited by one photobug; 07-10-2012 at 03:32 PM.
07-10-2012, 09:38 AM   #15
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The survey reports that 6 out of 107 have failed. To me, that's a very high number and one that should cause concern for any manufacturer. Some have rightfully stated that people tend to post when they are dissatisfied with something, and I agree, but the other side of this coin is how many people got pissed off and switched brands - thus never reported their problem in this poll? Pentax doesn't have to admit they have a problem to fix it, but it sure would have been nice for them to at least stand behind the ones that broke outside the warranty period as a show of good faith. The recent failure of my 300mm, which has been babied and used very little, has left me wondering if I'll ever buy another SDM Pentax lens.
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